1. Field of the Invention
This invention relates to a semiconductor memory cell, and particularly to a one-transistor/one-capacity type DRAM (Dynamic Random Access Memory) cell for holding information therein by electric charges stored in a capacitor.
2. Description of the Related Art
With the development of mass storage capacity of a DRAM, the areas of cells, each of which constitutes a one-bit storage element, have been recently reduced every year. However, the achievement of stable operation of a circuit needs to ensure an electrostatic capacity exceeding some degree of capacity. Therefore, a stacked-capacitor cell or the like for forming a capacity between polysilicon layers formed in a few layers is used as a structure of a cell capacitor.
This has been disclosed in various literature (e.g., Japanese Patent Application Laid-Open No. 4-274360).
The present invention to be described later should be understood integrally with this literature. The present invention has been completed with a view toward providing a semiconductor memory cell capable of ensuring a large surface area of each of the storage electrodes thereby increasing the capacity of a capacitive portion (capacitor) formed between the storage electrode and a cell plate electrode, in other words, greatly increase the capacity of the memory cell as compared with those described in the literature.